Borrowing Hydrogen for Organic Synthesis

ACS Central Science, Journal Year: 2021, Volume and Issue: 7(4), P. 570 - 585

Published: March 25, 2021

Borrowing hydrogen is a process that used to diversify the synthetic utility of commodity alcohols. A catalyst first oxidizes an alcohol by removing form reactive carbonyl compound. This intermediate can undergo diverse range subsequent transformations before returns "borrowed" liberate product and regenerate catalyst. In this way, alcohols may be as alkylating agents whereby sole byproduct one-pot reaction water. recent decades, significant advances have been made in area, demonstrating many effective methods access valuable products. outlook highlights diversity metal biocatalysts are available for approach, well various performed, focusing on selection most advances. By succinctly describing conveying versatility borrowing chemistry, we anticipate its uptake will increase across wider scientific audience, expanding opportunities further development.

Language: Английский

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Alcohols as Substrates in Transition-Metal-Catalyzed Arylation, Alkylation, and Related Reactions

Chemical Reviews, Journal Year: 2024, Volume and Issue: 124(9), P. 6078 - 6144

Published: April 17, 2024

Alcohols are abundant and attractive feedstock molecules for organic synthesis. Many methods their functionalization require them to first be converted into a more activated derivative, while recent years have seen vast increase in the number of complexity-building transformations that directly harness unprotected alcohols. This Review discusses how transition metal catalysis can used toward this goal. These broadly classified three categories. Deoxygenative functionalizations, representing derivatization C–O bond, enable alcohol act as leaving group formation new C–C bonds. Etherifications, characterized by O–H represent classical reactivity has been modernized include mild reaction conditions, diverse partners, high selectivities. Lastly, chain reactions described, wherein acts mediator formal C–H alkyl backbone. Each these classes transformation will discussed context intermolecular arylation, alkylation, related reactions, illustrating alcohols harnessed

Language: Английский

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Recent advances in nickel-catalyzed C–C and C–N bond formation via HA and ADC reactions

Organic & Biomolecular Chemistry, Journal Year: 2021, Volume and Issue: 19(19), P. 4213 - 4227

Published: Jan. 1, 2021

In this review article, recent advances in nickel-catalyzed hydrogen auto-transfer (HA) and acceptorless dehydrogenative coupling (ADC) reactions for the construction of C–C C–N bonds have been discussed.

Language: Английский

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Recent Progress in the Synthesis of Heterocycles through Base Metal‐Catalyzed Acceptorless Dehydrogenative and Borrowing Hydrogen Approach

European Journal of Organic Chemistry, Journal Year: 2021, Volume and Issue: 2021(26), P. 3690 - 3720

Published: June 15, 2021

Abstract Development in the area of acceptorless dehydrogenation (AD) and borrowing hydrogen (BH) catalysis emerge as one potential tools for various C−C C‐heteroatom bond forming reactions. Alcohols, which are important lignocellulosic biomass products, act pivotal electrophilic coupling partners such processes interestingly only H 2 or O is eliminated a byproduct. Initially, was developed by use noble metal catalysts. Recently, base metals Mn, Fe, Co, Ni proved to be environmentally benign inexpensive alternatives application AD BH methods. This transition catalyzed approaches also allow access toward plethora structurally heterocyclic molecules via atom economical strategy. Herein, we summarize current rising expansion heterocycles synthesis through hydrogenation

Language: Английский

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Metal–ligand cooperative approaches in homogeneous catalysis using transition metal complex catalysts of redox noninnocent ligands

Organic & Biomolecular Chemistry, Journal Year: 2021, Volume and Issue: 20(2), P. 296 - 328

Published: Dec. 6, 2021

Catalysis offers a straightforward route to prepare various value-added molecules starting from readily available raw materials. The catalytic reactions mostly involve multi-electron transformations. Hence, compared the inexpensive and 3d-metals, 4d 5d-transition metals get an extra advantage for performing as heavier transition prefer two-electron redox events. However, sustainable development, these expensive scarce heavy metal-based catalysts need be replaced by inexpensive, environmentally benign, economically affordable 3d-metal catalysts. In this regard, metal-ligand cooperative approach involving metal complexes of noninnocent ligands attractive alternative. synergistic participation redox-active during electron transfer events allows transformations using interesting chemical 5d-metals well. Herein we summarize up-to-date literature report on approaches few selected types reactions.

Language: Английский

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Well-Defined NNS-Mn Complex Catalyzed Selective Synthesis of C-3 Alkylated Indoles and Bisindolylmethanes Using Alcohols

The Journal of Organic Chemistry, Journal Year: 2022, Volume and Issue: 87(6), P. 3989 - 4000

Published: March 8, 2022

Herein, we demonstrated Mn-catalyzed selective C-3 functionalization of indoles with alcohols. The developed catalyst can also furnish bis(indolyl)methanes from the same set substrates under slightly modified reaction conditions. Mechanistic studies reveal that is going via a borrowing hydrogen pathway. To highlight practical utility, diverse range including nine structurally important drug molecules are synthesized. Furthermore, introduced one-pot cascade strategy for synthesizing functionalized directly 2-aminophenyl ethanol and alcohol.

Language: Английский

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Guerbet-type β-alkylation of secondary alcohols catalyzed by chromium chloride and its corresponding NNN pincer complex

Catalysis Science & Technology, Journal Year: 2022, Volume and Issue: 12(15), P. 4753 - 4762

Published: Jan. 1, 2022

β-Alkylation of alcohols has been efficiently accomplished using readily available 3d metal Cr under microwave conditions in air. Well-defined molecular is involved with a KIE 7.33 and insertion α-alkylated ketone into Cr–H bond as the RDS.

Language: Английский

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Alcohol Dehydrogenation-Triggered Selective C3-Alkylation of Indoles by Homogeneous Azo-aromatic Cobalt Catalysts

The Journal of Organic Chemistry, Journal Year: 2023, Volume and Issue: 88(9), P. 5827 - 5843

Published: April 10, 2023

Herein, we report azo-benzimidazole containing cobalt complexes (1-3) for alcohol dehydrogenation-triggered C3-alkylation of indoles. In 1-3, ligands are redox noninnocent and showed facile irreversible L/L• reduction followed by Co(II)/Co(I) in close-lying potentials. Taking advantage events the first aerial dehydrogenation alcohols to their corresponding carbonyl compounds is explored. Subsequently, indole was studied using as alkylating agents. The developed catalytic protocol found be efficient very selective. It has a broad substrate scope good functional group tolerance. As far aware, it homogeneous catalyst agent. Detailed mechanistic studies, including deuterium labeling experiment, have suggested borrowing hydrogen method indole. coordinated ligand, cooperatively with couple, oxidized alkoxide radical pathway result compound (Scheme 1), which on subsequent condensation generates alkylideneindolenine intermediate "X". Reduction "X" an azo-anion Co(I) resulted C3-alkylated

Language: Английский

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Zn(II)‐Stabilized Azo‐Anion Radical Catalyzed Sustainable C−C Bond Formation: Regioselective Alkylation of Fluorene, Oxindole, and Indoles

ChemCatChem, Journal Year: 2024, Volume and Issue: 16(10)

Published: Feb. 7, 2024

Abstract Herein we report a sustainable approach for the alkylation of ketones, 9 H ‐fluorene, oxindole, and indole using alcohols as alkylating agent catalyzed by well‐defined air‐stable zinc catalyst ( 1 ) tridentate redox non‐innocent arylazo ligand, 2‐((4‐chlorophenyl)diazenyl)‐1,10‐phenanthroline L ). 2–3 mol % efficiently produces substituted α‐alkylated 9‐alkylated fluorenes, C3 ‐alkylated oxindoles, indoles in moderate to good isolated yields. In aerial condition, formation bis(indolyl)methane (BIMs) derivatives were observed when subjected primary alcohols. A few drug molecules containing BIMs prepared The exhibited chemoselectivity during functionalization fluorene with oleyl alcohol β‐citronellol. control experiments, including deuterium labeling performed unveil reaction mechanism indicate that one‐electron reduced azo‐anion radical species [ ]‐formed situ, acts active catalyst. All events occur at redox‐active aryl‐azo which reservoir hydrogen electrons throughout catalytic cycle, keeping Zn(II)‐center template.

Language: Английский

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Cobalt-catalysed CH-alkylation of indoles with alcohols by borrowing hydrogen methodology

Green Chemistry, Journal Year: 2022, Volume and Issue: 24(11), P. 4566 - 4572

Published: Jan. 1, 2022

A general heterogeneous cobalt-catalysed CH-alkylation of indoles with alcohols is reported.

Language: Английский

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